Hyperspectral imaging usually incorporates division of the electromagnetic spectrum into many separate wavelength bands, which may be located in the infrared, visible, or ultraviolet regions. Images are obtained in which each spatial location contains spectral information that is useful in a number of fields. In particular, each wavelength band may carry different or additional information. Thus high resolution spectral information in combination with the spatial information is suitable for identification of chemical species, and objects by their chemical make up.
Civilian applications of hyperspectral imaging include weather observation, measurement of oxygenation patterns in tissues, geological mapping, industrial process control, and astronomy. Specific military applications include target identification, including discrimination of target simulators from real targets, and assessment of target destruction. Target identification, target discrimination, and assessment of target destruction are all of use in missile systems.
Some chemical targets have telltale spectral feature that require very high resolution spectroscopy to identify, and with spectral peaks located octaves apart in wavelength. Typically these spectra can be measured with a Fourier transform infrared spectrometer (FTIR). However, this scanning device takes minutes to gather the data. Slit spectrometer can be used for this purpose but their throughput is low, they can be very large, and their spectral coverage is limited to a single octave.
Spatial Heterodyne Spectrometers (SHS) are typically spectrometers capable of observing spectra of light radiated from or reflected by a target in a narrow band of wavelengths.
Spatial heterodyne spectrometers have also been known as Heterodyned Holographic Spectrometers, as for example in “An Astronomical Seismometer”, Frandsen et. al, Astron. Astrophys. 279 310-321, 1993. In this article, Frandsen et. al describe a single-band SHS operating at a single diffraction grating order but having a post-dispersion grating for isolating spectral lines near the center wavelength of the spectrometer.